Polarizers coated with optically functional layers

ABSTRACT

An optical stack includes an intrinsic polarizer, such as a K-type or thin KE polarizer sheet. Optically functional coatings are disposed on one or both of the surfaces of the intrinsic polarizer. The optically functional coatings include a hardcoat, a transflector coating, a reflector coating, an antireflection film, a liquid crystal polymer retarder coating, a diffusion coating, an antiglare film, a wide view film, and an electrode. An optical stack including an intrinsic polarizer and an optically functional coating may have a thickness of less than 25 microns.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of prior application Ser. No.09/897,865, filed on Jul. 2, 2001, now U.S. Pat. No. 7,110,178, thecontents of which is incorporated by reference in its entirety herein.

BACKGROUND

This invention relates to polarizers such as those used in liquidcrystal displays, and more particularly to polarizers coated withoptically functional layers.

Liquid crystal displays are optical displays used in devices such aslaptop computers, hand-held calculators and digital watches. A typicalliquid crystal display includes a liquid crystal display cell and anelectrode matrix disposed between a pair of absorbing polarizers. Theliquid crystal display cell contains, e.g., twisted nematic or supertwisted nematic molecules. In the liquid crystal display, the opticalstate of portions of the liquid crystal display cell is altered by theapplication of an electric field using the electrode matrix. Thiscreates an optical contrast for light passing through the liquid crystaldisplay cell that results in the appearance of pixels of polarized lighton the liquid crystal display.

A typical liquid crystal display includes a front polarizer and a rearpolarizer. These polarizers may be plane polarizers that absorb light ofone polarization orientation more strongly than they absorb light of theorthogonal polarization orientation. The transmission axis of the frontpolarizer is usually crossed with the transmission axis of the rearpolarizer in a liquid crystal display. The angle by which thesetransmission axes are crossed can vary from zero degrees to ninetydegrees.

In general, unpolarized ambient light waves vibrate in a large number ofdirections without having a single characterizing electromagneticradiation vector. By contrast, plane polarized light consists of lightwaves having a direction of vibration along a single electromagneticradiation vector. Also, circularly polarized light has a direction ofvibration along an electromagnetic radiation vector that rotates as thelight propagates through space. Polarized light has many applications inelectro-optical devices, such as the use of plane and circularpolarizing filters to reduce glare in displays.

Further, much commercial attention has been directed to the developmentand improvement of flat panel displays, particularly thin, compact flatpanel displays. A problem encountered in the construction of plasticflat panel displays is the development of “black spots,” which arisefrom the formation of bubbles in the liquid crystal material from gasthat has permeated through the plastic display materials. Anotherproblem associated with plastic flat panel displays is moisturecontamination of the liquid crystal display cell. These problems areavoided in conventional liquid crystal displays by using lowpermeability glass substrates instead of plastic. With respect toplastic flat panel displays, these problems are addressed by addingadditional gas and moisture barrier layers to the liquid crystal displaystructure and/or the plastic substrates. However, adding such gas andmoisture barrier layers increases the thickness, weight and cost of thedisplays.

Polarizers in the form of synthetic polarizing films exhibit comparativeease of manufacture and handling and comparative ease with which theymay be incorporated into electro-optical devices such as flat paneldisplays. In general, plane polarizing films have the property ofselectively passing radiation vibrating along a given electromagneticradiation vector and absorbing electromagnetic radiation vibrating alonga second electromagnetic radiation vector based on the anisotropiccharacter of the transmitting film medium. Plane polarizing filmsinclude dichroic polarizers, which are absorbing plane polarizersutilizing the vectorial anisotropy of their absorption of incident lightwaves. The term “dichroism” refers to the property of differentialabsorption of the components of incident light, depending on thevibration directions of the component light waves. Light entering adichroic plane polarizing film encounters two different absorptioncoefficients along transverse planes, one coefficient being high and theother coefficient being low. Light emerging from a dichroic filmvibrates predominantly in the plane characterized by the low absorptioncoefficient.

Dichroic plane polarizing films include H-type (iodine) polarizers anddyestuff polarizers. For example, an H-type polarizer is a syntheticdichroic sheet polarizer including a polyvinyl alcohol-iodine complex.Such a chemical complex is referred to as a chromophore. The basematerial of an H-type polarizer is a water-soluble high molecular weightsubstance, and the resulting film has relatively low moisture and heatresistance and tends to curl, peel or otherwise warp when exposed toambient atmospheric conditions. Further, H-type polarizers areinherently unstable, and require protective cladding, e.g., layers ofcellulose triacetate, on both sides of the polarizer to preventdegradation of the polarizer in a normal working environment such as ina liquid crystal display.

In contrast to H-type polarizers and other similar synthetic dichroicplane polarizers are intrinsic polarizers and thinly cladded orencapsulated polarizers. Intrinsic polarizers polarize light due to theinherent chemical structure of the base material used to form thepolarizer. Such intrinsic polarizers are also typically thin anddurable. Examples of intrinsic polarizers are K-type polarizers. Athinly cladded or encapsulated polarizer may be, e.g., an iodinepolarizer coated on both surfaces with polymer coatings each having athickness of only about 5 microns, and is also thin and durable.

A K-type polarizer is a synthetic dichroic plane polarizer based onmolecularly oriented polyvinyl alcohol (PVA) sheets or films with abalanced concentration of light-absorbing chromophores. A K-typepolarizer derives its dichroism from the light absorbing properties ofits matrix, not from the light-absorbing properties of dye additives,stains, or suspended crystalline materials. Thus, a K-type polarizer mayhave both good polarizing efficiency and good heat and moistureresistance. A K-type polarizer may also be very neutral with respect tocolor.

An improved K-type polarizer, referred to as a KE polarizer, ismanufactured by 3M Company, Norwood, Mass. The KE polarizer has improvedpolarizer stability under severe environmental conditions, such as hightemperatures and high humidity. In contrast to H-type polarizers, inwhich the light absorption properties are due to the formation of achromophore between PVA and tri-iodide ion, KE polarizers are made bychemically reacting the PVA by an acid catalyzed, thermal dehydrationreaction. The resulting chromophore, referred to as polyvinylene, andthe resulting polymer may be referred to as a block copolymer ofvinylalcohol and vinylene.

For H-type polarizers, stability is achieved by sandwiching thepolarizer between two plastic substrates, such as two layers ofcellulose triacetate, one on each side of the polarizer. However, evenin these structures the application of heat, humidity and/or vacuum canadversely affect the properties of the polarizer. By contrast, K-typepolarizers such as KE polarizers do not need to be sandwiched betweensheets of cellulose triacetate. The polyvinylene chromophore of the KEpolarizer is an extremely stable chemical entity, since the chromophoreis intrinsic to the polymer molecule. This chromophore is thermallystable as well as resistant to attack from a wide range of solvents andchemicals.

A K-type polarizer such as a KE polarizer has several advantages overother types of polarizers, e.g., iodine and dyestuff polarizers. K-typepolarizers have more durable chromophores, are thinner, and may bedesigned with variable transmission levels. Most notably, K-typepolarizers such as KE polarizers may be used in applications thatrequire high performance under severe environmental conditions,including high temperatures and high humidity, such as 85° C. and 85%relative humidity, for extended periods of time. Under such extremeenvironmental conditions, the stability of iodine polarizers is greatlyreduced, thus limiting their usefulness in applications such as flatpanel displays. Due to the inherent chemical stability of K-typepolarizers, a wide variety of adhesive formulations, including pressuresensitive adhesives, can be applied directly to K-type polarizers.Further, a single-sided plastic support is adequate to give physicalsupport for K-type polarizers, and since this support can be locatedoutside of the optical path of the liquid crystal display cell, it neednot be optically isotropic and lower-cost substrates such aspolyethylene terephthalate (PET) are acceptable alternatives. Moreover,the ability to construct single-sided laminates allows the opticalstructures to be thinner, allowing for additional flexibility in thedesign and manufacture of flat panel display elements. These advantagesof K-type polarizers may be used in a wide variety of opticalapplications, including flat panel displays.

In contrast to a plane polarizer, a circular polarizer may beconstructed of a plane polarizer and a quarter-wavelength retarder. Aquarter-wavelength retarder shifts the phase of light waves propagatingalong one plane through the retarder by one-quarter wavelength, but doesnot shift the phase of light waves propagating through the retarderalong a transverse plane. The result of combining light waves that areone-quarter wavelength out of phase and that vibrate along perpendicularplanes is circularly polarized light, for which the electromagneticradiation vector rotates as the combined light waves travel throughspace.

Circularly polarized light may be described with respect to two distinctpolarization states: left-handed (L) and right-handed (R) circularlypolarized light. A circular polarizer absorbs light of one of thesepolarization states and transmits light of the other polarization state.The use of circular polarizers to reduce glare in displays is wellknown. In particular, light from an emissive display can be selectivelytransmitted through a circular polarizer, while background ambient lightreflected in the display, which causes glare, may be reduced oreliminated.

A conventional liquid crystal display stack 100 is shown in FIG. 1. Aliquid crystal display cell 102 has two surfaces coated with layers 104,106 of an adhesive, e.g., a pressure sensitive adhesive, to securepolarizer structures to both surfaces of the liquid crystal displaycell. The polarizer structures each include plane polarizers 108, 110,e.g., H-type polarizers, which have layers 112, 114, 116, 118 ofcellulose triacetate as a protective cladding on both surfaces thereof.The layers of cellulose triacetate may be secured to the polarizers withlayers of adhesive 120, 122, 124, 126. Liquid crystal display stack 100also typically includes a transflector or reflector 30 attached to theback side of the display by an adhesive layer 32, e.g., a pressuresensitive adhesive, the transflector or reflector functioning to enhancethe brightness and contrast of the liquid crystal display. H-typepolarizers 108, 110 each typically have a thickness of approximately 20microns, each of the layers of cellulose triacetate is typicallyapproximately 80 microns thick, the pressure sensitive adhesive layerstypically have a thickness of approximately 25 microns each, and theother adhesive layers typically have a thickness of approximately 5microns each. Liquid crystal display stack 100 has a thickness of atleast about 455 microns, excluding the liquid crystal display cell andthe transflector.

Layers of adhesives, e.g., pressure sensitive adhesives, have previouslybeen applied to intrinsic polarizers such as KE polarizer sheets. Anadhesive layer may be used to adhere the polarizer to a liquid crystaldisplay cell or to another optically functional layer, which may itselfbe formed on a substrate such as polyethylene terephthalate (PET).Typically, the thickness of a polarizer such as a KE polarizer sheet isabout 20 microns, and the thickness of the adhesive layer is about 25microns.

SUMMARY

In general, in one aspect, the invention features an optical stackincluding an intrinsic polarizer having a first surface. A firstoptically functional coating is disposed on the first surface of theintrinsic polarizer.

Implementations of the invention may also include one or more of thefollowing features. The intrinsic polarizer may have a second surface,and the optical stack may also include a second optically functionalcoating disposed on the second surface of the intrinsic polarizer. Theintrinsic polarizer may be a K-type polarizer or a KE polarizer sheet.

The first optically functional coating may include a hardcoat, areflector coating, a liquid crystal polymer retarder coating, adiffusion coating, an antiglare film, a wide view film, or an electrode.The first optically functional coating may include a transflectorcoating, which may include a layer of metal. The first opticallyfunctional coating may include an antireflection film, which may includea plurality of polymer layers or inorganic layers.

The intrinsic polarizer may have a second surface, and the optical stackmay also include a layer of adhesive disposed on the second surface ofthe intrinsic polarizer. The intrinsic polarizer may be attached to aliquid crystal display cell by the layer of adhesive. The layer ofadhesive may include a pressure sensitive adhesive or a diffuseadhesive.

In general, in another aspect, the invention features an optical stackincluding an intrinsic polarizer and an optically functional coating,wherein the thickness of the optical stack is less than 25 microns. Ingeneral, in another aspect, the invention features an optical stackincluding an intrinsic polarizer and an optically functional coating,wherein the thickness of the optical stack is about 25 microns.

In general, in another aspect, the invention features an optical stack,including a K-type polarizer having a first surface and a secondsurface. A first optically functional coating is disposed on the firstsurface of the K-type polarizer. A second optically functional coatingis disposed on the second surface of the K-type polarizer.

In general, in another aspect, the invention features a method offorming an optical stack. An intrinsic polarizer having a first surfaceand a second surface is provided. A first optically functional coatingis disposed on the first surface of the intrinsic polarizer.

Implementations of the invention may also include one or more of thefollowing features. The method may include disposing a second opticallyfunctional coating on the second surface of the intrinsic polarizer. Thedisposing step may include coating. The method may include disposing alayer of adhesive on the second surface of the intrinsic polarizer.

In general, in another aspect, the invention features an optical stackincluding a thinly cladded polarizer having a first surface. A firstoptically functional coating is disposed on the first surface of thethinly cladded polarizer.

In general, in another aspect, the invention features a method offorming an optical stack. A thinly cladded polarizer having a firstsurface is provided. A first optically functional coating is disposed onthe first surface of the thinly cladded polarizer.

An advantage of the present invention is elimination of the need forprotective cladding and support structures for the polarizers in theliquid crystal display stack, resulting in significant reduction in thethickness of the liquid crystal display. Thus, an additional advantageof the invention is the ability to manufacture thinner andlighter-weight liquid crystal displays. Another advantage of the presentinvention is that an intrinsic polarizer such as a K-type polarizerprovides stable performance over a wide range of transmission levels. Afurther advantage of the present invention is increased brightness ofliquid crystal displays using K-type polarizers compared to currentlymanufactured liquid crystal displays, with resulting lower energyrequirements for illumination of the display.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a conventional liquid crystaldisplay stack.

FIG. 2 is a cross sectional view of a polarizer with opticallyfunctional coatings according to the present invention.

FIG. 3 is a cross sectional view of a polarizer with an adhesive layerand an optically functional coating according to the present invention.

FIG. 4 is a cross sectional view of a polarizer with an antireflectioncoating according to the present invention.

FIG. 5 is a cross sectional view of an alternative embodiment of apolarizer with an antireflective coating.

FIG. 6 is a cross sectional view of a polarizer with a retarderaccording to the present invention.

FIG. 7 is a cross sectional view of a polarizer with a conductoraccording to the present invention.

FIG. 8 is a cross sectional view of an alternative embodiment of apolarizer with optically functional coatings according to the presentinvention.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

The present invention relates to polarizers coated with opticallyfunctional layers, which may be used in liquid crystal displays.

FIG. 2 shows an optical stack 20, which includes a polarizer 22 having afirst surface 24 and a second surface 26. Optically functional layers28, 30 are coated directly onto the first and second surfaces ofpolarizer 22, respectively. In a particular application, only one ofoptically functional layers 28, 30 need be present on one of thesurfaces of polarizer 22.

Polarizer 22 is preferably an intrinsic polarizer, such as a K-typepolarizer or thin KE polarizer sheet. The intrinsic polarizer may be,e.g., a KE polarizer such as a sheet of the type manufactured by 3MCompany, Norwood, Mass. A KE polarizer sheet may have a thickness ofapproximately 20 microns.

Optically functional layers 28, 30 may be coated directly onto anintrinsic polarizer 22, such as a K-type polarizer, due to themechanical and chemical durability of the polarizer, and withoutrequiring the use of an additional substrate such as polyethyleneterephthalate (PET). Using a K-type polarizer in a liquid crystaldisplay stack also eliminates the need for additional protectivecladding of the polarizers. The cladding used for other types ofpolarizers, e.g., H-type polarizers, is generally a layer of cellulosetriacetate disposed on both sides of the polarizer. Removing thecladding layers of cellulose triacetate results in a significantreduction in the thickness of the liquid crystal display stack.

Further, the use of K-type polarizers in liquid crystal display stackscould provide an effective gas and moisture permeability barrier to theliquid crystal material in the liquid crystal display cell. Thus, noadditional barrier layers or cladding may be needed in a liquid crystaldisplay structure constructed with a K-type polarizer disposed on eachside of the liquid crystal display cell to achieve desired permeabilityspecifications. In particular, a standard for moisture vaportransmission rate (MVTR), ASTM F1249, is less than 20 gm/m²/day, and theoxygen transmission rate (O2GTR), ASTM D3985, is less than 1 ml/m²/day.Structures for liquid crystal displays formed using KE polarizers,including PET support structures, have been shown to have a MVTR of 4.6or less gm/m2/day and an O2GTR of less than 0.005 ml/m²/day (tested at20° C. and 90% relative humidity).

FIG. 8 shows an alternative embodiment of the invention, in whichpolarizer 22 is a thinly cladded or encased iodine polarizer. The thinlycladded polarizer includes an iodine polarizer sheet 400 coated on bothsurfaces with polymer coatings 402, 404 each having a thickness of about5 microns. Optically functional layers 28, 30 are coated directly ontopolymer coatings 402, 404. The thinly cladded polarizer is thin anddurable, similar to an intrinsic polarizer such as a K-type polarizer.

FIG. 3 shows a layer of an adhesive 40, e.g., a pressure sensitiveadhesive such as Kayapolar, coated onto one of the surfaces of polarizer22. Adhesive layer 40 may be used to secure polarizer 22 to a liquidcrystal display cell 42. An adhesive other than a pressure sensitiveadhesive, e.g., a coated, urethane-based adhesive that is thermallycured such as a copolyester adhesive that is crosslinked usingmultifunctional isocyanates, may be used. An optically functionalcoating 30 may also coated onto the other surface of polarizer 22.

Each of optically functional layers 28, 30 may be, e.g, a hardcoat, atransflector coating, a reflector coating, an antireflection film, aliquid crystal polymer retarder coating, a diffusion coating, anantiglare film, a wide view film, or an electrode.

A hardcoat, which typically has a thickness of 1-6 microns, may be made,e.g., from an acrylate such as poly methyl methacrylate. The hardcoatmay be either matte or clear. Alternatively, the hardcoat may betextured, e.g., by microreplication, to include beam steering propertiesor a matte appearance.

Referring to FIG. 2, a transflector coating or a reflector coating 30may be disposed on the surface of intrinsic polarizer 22 facing the backside of the liquid crystal display to enhance the brightness andcontrast of the liquid crystal display. A transflective coating may havea thickness of approximately 5-20 microns. The transflective coating maybe, e.g., a nacreous pigment such as commercially available STR400 fromNippon Paper or a transflector material available from Teijin.Alternatively, a transflector or reflector coating may be in the form ofa layer of metal such as silver or aluminum, which acts as a polarizedmirror to reflect polarized light and enhance the brightness of theliquid crystal display. Such a transflector or reflector coating may beformed by sputtering, vacuum depositing, or otherwise coating a layer ofsilver or aluminum onto a K-type polarizer. Another example of atransflector is a coating of mica on a polymer or adhesive matrix.

An antireflection coating, which may have a thickness of less than 1micron, may be made from a low index of refraction thermopolymer such asKynar 1702. For example, as shown in FIG. 4, an antireflection coatingformed on a KE polarizer sheet 50 has a high-refractive index hardcoat52 and a low-refractive index antireflection layer 54. The hardcoatpreferably has a refractive index greater than about 1.6, and athickness of approximately 5-10 microns. The antireflection layerpreferably has a refractive index less than about 1.5, and a thicknesson the order of 0.1 micron, which corresponds to about one-quarter ofthe wavelength of visible light. Since a KE polarizer sheet has athickness of about 20 microns, the total thickness of the optical stackshown in FIG. 4 may be less than 26 microns.

An antireflection coating may also have one or more antireflectionlayers, with the layers preferably having alternating high and lowindices of refraction, because the optical performance of anantireflection film increases with the number of layers. Such amultilayer antireflection film preferably has a series of highly uniformpolymer or inorganic layers formed by web coating, sputtering, or both.Thus, as shown in FIG. 5, a coating having, e.g., four polymer and orinorganic layers 56, 58, 60, 62, may be formed on hardcoat 52. Thethicknesses of the polymer or inorganic layers also preferably increasewith the distance from the hardcoat. Nevertheless, the total thicknessof the multiple polymer or inorganic layers may be on the order of 0.1micron, so that the total thickness of the optical stack shown in FIG. 5may also be less than 26 microns.

A liquid crystal polymer coating, which typically has a thickness of upto approximately 100 microns, may function as a retarder or negativedispersion compensation film to enhance the color and contrast of aliquid crystal display by changing the phase of light passing throughthe retarder. Such a retarder is preferably a thin film, broadbandquarter-wavelength retarder or negative dispersion compensation filmeffective over all or a substantial portion of the visibleelectromagnetic spectrum, such as the broadband quarter-wavelengthretarders manufactured by Teijin. For example, the typical thickness ofquarter-wavelength retarder is approximately 30-60 microns.Alternatively, the retarder or negative dispersion compensation film maybe a polycarbonate based retarder or an Arton-type resin retarder.

The combination of an intrinsic polarizer with a retarder acts as acircular polarizer, which significantly reduces the intensity ofundesirable reflected ambient light, thereby increasing the contrast ofthe image formed by the emitted signal from the display. As shown inFIG. 6, unpolarized ambient light 202 may be represented as acombination of left-handed (L) 204 and right-handed (R) 206 circularlypolarized light components. When unpolarized ambient light 202 entersliquid crystal display 200, one circularly polarized component of theambient light, e.g., left-handed circular polarized light 204, isabsorbed by the combination of the intrinsic polarizer 22 and theretarder 30, while the other component, the right-handed circularlypolarized light 206, is transmitted through the liquid crystal display.The transmitted right-handed circularly polarized light 206 isspecularly reflected in the liquid crystal display. However, thehandedness of circularly polarized light is reversed upon specularreflection, and the transmitted right-handed circularly polarized light206 becomes left-handed circularly polarized light. The reflectedleft-handed circularly polarized light is reflected toward thecombination of the intrinsic polarizer with the retarder, where it isabsorbed in the same manner as the left-handed circularly polarizedcomponent 204 of ambient light 202. Thus, both the left-handed andright-handed circularly polarized components of the ambient light areabsorbed by the combination of the intrinsic polarizer and the retarder,which acts as a circular polarizer, during transmission through andreflection in liquid crystal display 200 so that they do not interferewith an emitted light signal 210.

A diffusion coating may be a diffuse adhesive that functions similarlyto the combination of an adhesive layer and a transflective coating toincrease the viewing angle of the liquid crystal display. For example, adiffuse adhesive may be a pressure sensitive adhesive to which glassbeads have been added to scatter light passing through the adhesive.Such a diffuse adhesive typically has a thickness of approximately 12-40microns. Alternatively, a diffusion layer may be a polymer film or apolymer matrix containing glass beads.

An antiglare film may be used to reduce the specular component ofreflection from a display surface, e.g., using a roughened surface. Suchan antiglare film may be made from an ultraviolet crosslinked polymer oran acrylate doped with poly methyl methacrylate or silica beads orparticles. An antiglare film may have a thickness, e.g., from about 1 toabout 12 microns.

A wide view film may be used to expand the viewing angle to a displaysurface. Such a wide view film typically has several layers of orientedliquid crystal polymers, i.e., with the molecules in a first layerorienting the molecules in an adjacent second layer.

Optically functional coatings 28, 30 may be applied to polarizer 22 byone or more standard coating methods. Applicable coating methodsinclude, but are not limited to, spin coating, sputtering, rod coating,gravure coating, slot dye coating, vacuum coating, knife coating, anddip coating.

FIG. 7 shows another embodiment of the present invention, in which anintrinsic polarizer such as a K-type or thin KE polarizer sheet is usedas a substrate for a conductor in a liquid crystal display withoutrequiring any adhesive for attaching the conductor. In polarizerstructure 300, a conductor 302 in the form of a conducting metal ormetal oxide layer 304, e.g., indium tin oxide (ITO), is disposed betweenlayers 306, 308, e.g., also of ITO. Layer 304 may be, e.g., silver,gold, or a mixture of silver and gold. Conductor 302 is formed on ahardcoat 30 directly on intrinsic polarizer 22. A conductor pattern maythen be etched into layers 304, 306, 308 of conductor 302.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

1. An optical stack, comprising: an intrinsic polarizer having a firstsurface and a second surface; an optically functional layer secured tothe first surface; and wherein the intrinsic polarizer is not directlyprotected or supported in the optical stack.
 2. The optical stack ofclaim 1 wherein the optically functional layer is effective over thevisible electromagnetic spectrum.
 3. The optical stack of claim 1wherein the optically functional layer is effective over the non-visibleelectromagnetic spectrum.
 4. The optical stack of claim 1 wherein theoptical stack does not include cellulose triacetate.
 5. The opticalstack of claims 2 or 3 and further comprising: a layer of adhesivedisposed on the second surface of the intrinsic polarizer.